Final answer:
The expression 9x^2 - 25 is a difference of squares and factors into (3x + 5)(3x - 5). The correct answer is A. (3x + 5)(3x - 5).
Step-by-step explanation:
To factor the quadratic expression 9x^2 - 25, we need to recognize it as a difference of squares. A difference of squares is a binomial of the form a^2 - b^2, which factors into (a + b)(a - b). In this specific case, 9x^2 is a perfect square, being (3x)^2, and 25 is also a perfect square, being 5^2.
Therefore, the factored form of the given expression is (3x + 5)(3x - 5). Matching this with the given choices, the correct answer is A. (3x + 5)(3x - 5).